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                     What Factors 
Influence the 
Choice Between 
Azure SQL 
Database and 
 Presented by: [Golla kalyan Visualpath]
Cosmos DB?
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Understanding Azure Data Storage Options
Azure provides a diverse portfolio of database services, each engineered to address specific application requirements 
and data workloads.
Among the most prominent are Azure SQL Database, a robust relational database service, and Azure Cosmos DB, a 
globally distributed, multi-model NoSQL database service.
The optimal choice between these two powerful options hinges on a careful assessment of several critical technical and 
business factors.
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Relational vs. Non-relational Data
Azure SQL Database Azure Cosmos DB
Designed for structured, relational data where data integrity and A multi-model NoSQL database supporting various data models 
well-defined schemas are paramount. Ideal for traditional like document (JSON), key-value, column-family, and graph. Flexible 
applications requiring ACID (Atomicity, Consistency, Isolation, schema allows for rapid iteration and handling of unstructured or 
Durability) properties. semi-structured data.
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How Performance Needs Affect Selection
Azure SQL Scaling Cosmos DB Scaling
Offers vertical scaling (scaling up) by increasing Provides horizontal scaling (scaling out) and global 
compute tiers (DTUs or vCores) to handle higher distribution. Data is automatically partitioned across 
workloads on a single instance. Best for predictable multiple regions, enabling extremely low-latency reads 
growth and contained data volumes. and writes at a global scale.
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Geographical Reach and Data Replication
Cosmos DB: Global by Design Azure SQL: Geo-Replication
Offers native multi-region write and read capabilities with Supports geo-replication for disaster recovery and read-scale out, 
automatic data replication across Azure regions. This allows but configuration is more manual. Write operations are typically 
applications to have data geographically close to users, reducing confined to a single primary region, with replicas for read operations 
latency and increasing availability. or failover.
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Data Consistency Models Matter
Cosmos DB Flexibility
Offers five well-defined consistency levels: Strong, Bounded Staleness, 
Session, Consistent Prefix, and Eventual. This allows developers to fine-
tune the balance between consistency, availability, and latency based on 
application needs.
1 2
Azure SQL: ACID Compliance
Adheres to traditional ACID (Atomicity, Consistency, Isolation, 
Durability) transaction properties, ensuring strong consistency for all 
operations. Ideal for applications where data integrity is paramount and 
real-time consistency is non-negotiable.
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Query Support and Developer Experience
Query Language T-SQL (Transact-SQL) SQL API (for JSON), MongoDB API, Cassandra API, Gremlin 
API, Table API
Schema Strict, pre-defined schema Schema-agnostic (flexible)
Joins Complex relational joins Limited, typically denormalized for performance
SDKs ADO.NET, JDBC, ODBC, etc. Many languages (C#, Java, Python, Node.js, Go)
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Pricing Considerations
DTU/vCore RU/s
Azure SQL Database Azure Cosmos DB
Pricing is primarily based on DTUs (Database Pricing is based on provisioned throughput (Request 
Transaction Units) or vCores, which bundle compute, Units per second - RU/s), which abstracts CPU, memory, 
memory, and I/O resources. Costs are generally and I/O. This model offers high cost-efficiency for highly 
predictable for stable workloads but can escalate with variable or globally distributed workloads due to its 
sudden spikes. elasticity.
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Making the Right Choice
Azure SQL Database Azure Cosmos DB Key Assessment Areas
Ideal for traditional OLTP (Online Preferred for modern, real-time Evaluate your data's structure, 
Transaction Processing) applications (e.g., IoT, mobile), performance requirements, 
applications, existing relational globally distributed solutions, and geographical distribution needs, 
workloads, and systems requiring scenarios demanding high and budget. These factors will 
strong transactional consistency throughput, low latency, and guide you toward the most 
with complex joins. schema flexibility. suitable Azure database service.
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For More Information About 
  Azure Solutions Architect 
Address:- Flat no: 205, 2nd Floor,
   Nilagiri Block, Aditya Enclave,  Ameerpet, 
Hyderabad-16
   Ph. No: +91-998997107
  www.visualpath.in
    [email protected]
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Thank You
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